~Dr. Gabe Mirkin's Fitness and Health e-Zine
Recent studies show that both taking in too little and too much salt can cause high blood pressure to increase your risk for heart attacks and strokes. Most North Americans can get all the salt they need without using a salt shaker because:
If you doubled or tripled your salt losses through sweating, you may still not be deficient because you probably take in far more salt than you need.
* High blood pressure: The people who are most likely to develop high blood pressure from excess salt intake are those who have high blood sugar levels (Lancet, March 2, 2009). A review of the world’s literature shows that salt restriction does not lower high blood pressure for most people with high blood pressure (Journal of Hypertension, May 2011;29(5):821-828).
* Excess weight: A recent study showed that excess salt makes you hungry and decreases thirst, so excess salt can make you gain weight (Journal of Clinical Investigation, April 17, 2017). First, excess salt causes your adrenal glands to make cortisones that make you hungry, not thirsty. Second, excess salt can damage muscle and fat cells in your body. Excess salt accumulates first outside the cells, then enters muscle and fat cells, drawing extra water into these cells, which can cause the cells to swell and burst (Journal of the American College of Cardiology, March, 2015;65(10)). Then to replace the damaged fat and muscle cells, you become hungry and eat more food. The extra food is used for the energy and nutrients to replace the damaged cells. The end products of converting food to energy are carbon dioxide and water, so these reactions cause your body to produce extra water and therefore you do not feel not thirsty. However, you have increased your intake of food and calories and can gain weight.
* High blood sugar: Extra salt stimulates your adrenal glands to increase your body's production of glucocorticoids (cortisol, cortisone) that raise blood sugar levels.
* Night time urination: Excess salt in your urine can increase urination (International Journal of Urology, Mar 14, 2017;24(3)).
If you have any of these conditions, you may want to consider whether excess salt may be a factor.
More than 90 percent of North Americans will eventually develop high blood pressure, but excess salt is not necessarily the cause. The people most likely to suffer high blood pressure from excess salt intake are those who are insulin insensitive (Hypertension, Jan 2013). They are the people who suffer from diabetes or from high blood sugar levels called metabolic syndrome (Lancet, published online March 2, 2009). People with high blood sugar levels are usually overweight, do not exercise, have low blood levels of hydroxy vitamin D (<20 ng/ml), store fat primarily in their bellies, have a thick neck, high blood triglycerides, low blood good HDL cholesterol, and eventually all the side effects of diabetes. People with metabolic syndrome have a greater rise in blood pressure with increased salt intake and a drop in blood pressure with salt restriction. The more risk factors for metabolic syndrome a person has, the greater the rise and fall of blood pressure with changes in salt intake.
Check your blood pressure twice each day, during the day and before you go to bed at night. Take only a single reading each time and then average the blood pressures over the week for both daytime and bedtime readings. Normal blood pressure is significantly higher during the day than it is at night before you go to bed or in the morning when you first wake up. You have high blood pressure if the systolic pressure is above 120 mm Hg before you go to bed or when you first wake up in the morning, or if it is above 139 during the day.
Everyone needs salt. Your blood sodium (salt) level is too low when it is below 130 mEq/L. Salt restriction may result in delayed recovery from previous exercise, muscle weakness, pain and cramps, fatigue, nausea and vomiting, headache, confusion, loss of appetite, restlessness, irritability, seizures, falling, difficulty walking and inability to concentrate.
A study of 130,000 people from 49 countries showed that severely restricting salt may actually increase risk for heart attacks, strokes and death in both people with and without high blood pressure (Lancet, May 20, 2016). Other studies support this study by showing that a moderate salt intake (three to six grams per day) is associated with reduced risk of heart attacks and death compared to an intake of less than three grams per day (N Engl J Med, Aug 14, 2014;371(7):612-23). The highest risk for heart attacks occured in people who take in fewer than three grams or more than six grams of salt each day.
Both too much salt and too little salt can cause high blood pressure. A report analyzing 23 different studies of 274,683 participants showed that taking in too little salt may be even more likely than too much salt to cause high blood pressure and premature death (American Journal of Hypertension, April 1, 2014). The Institute of Medicine issued a report concluding that there was insufficient evidence to conclude that severe salt restriction (reducing daily sodium intake to less than 2,300 mg) reduces risk for heart attacks or death. When your body is low on salt, your adrenal glands produce large amounts of aldosterone and your kidneys produce large amounts of renin to help you retain the salt that you have left in your body. Both of these hormones also constrict your blood vessels which can raise blood pressure significantly.
The only mineral that you need to replace during exercise lasting longer than three hours is sodium, found in common table salt. You do not need to take extra potassium, magnesium or any other mineral during exercise. Salt tablets can burn holes in your stomach and salty drinks taste awful, so it is easier to meet your needs with salted foods. If you plan to exercise for more than a couple hours in hot weather, drink one or two cups of the liquid of your choice each hour and eat salty foods such as salted peanuts or potato chips.
Salt deficiency causes tiredness, lethargy and cramps. It also weakens muscles, causing you to slow down and lose strength. If you suffer any of these symptoms, you can get a blood test for sodium and chloride on the day after a hard workout. Low blood levels of sodium are most likely to occur on the morning after you have replaced fluid lost from heavy exercise. If your blood sodium level is below 130, you are deficient and need to add more salt to your food.
I recommend that you continue to follow the heart-healthy diet that I have advocated for many years. This way of eating is relatively low in salt because you eat lots of plants and fresh foods that have not been altered by food manufacturers.